The present invention relates to making composite material parts that are bodies of revolution, and more particularly to making and winding fiber textures that are to constitute the fiber reinforcement of such parts.
The field of application of the invention is more particularly making parts that are bodies of revolution out of structural composite material, i.e. structural parts comprising fiber reinforcement densified by a matrix. Composite materials enable parts to be made presenting overall weight that is smaller than the same parts would have if they were made out of metal.
For a part that constitutes a body of revolution, such as for example an aeroengine casing, the fiber preform that is to form the reinforcement of the part is made from a fiber texture that is wound on support tooling.
More precisely, and as shown in FIG. 1, a fiber texture 10 in the form of a strip is woven as a single piece by three-dimensional (3D) or multilayer weaving between a plurality of layers of warp yarns. The 3D or multilayer weaving of the fiber texture 10 is performed in a loom 20 of Jacquard type, with weaving consisting in inserting weft yarns 12 so as to create a pattern between warp yarns 11. At the outlet from the loom 20, the fiber texture 10 is wound on support tooling 30 comprising a mandrel 31 presenting an outside surface 31a onto which the fiber texture 10 is wound.
A fiber preform is then made by winding the fiber texture 10 under tension onto a mold tooling. As shown in FIG. 2, intermediate conveyor rollers 40 and 50 are used for making the tension uniform across the width of the fiber texture 10 while it is being wound under tension onto a mold tooling 60, the texture 10 being unwound from the support tooling 30. The mold tooling 60 comprises a mandrel 61 having an outside surface onto which the fiber texture 10 is wound under tension, said outside surface presenting a shape that corresponds to the shape of the composite material part that is to be made. The fiber texture 10 is held on the mandrel 61 of the mold tooling 60 by means of a shoe 62 that is removed between turns in order to be able to wind the following turn.
At the end of winding, i.e. after a plurality of turns of fiber texture 10 have been made on the mold tooling 60 so as to form a fiber preform 80, a shoe 62 is put into position once more in order to hold the preform 80 in place and prevent it from unwinding while it is being cut by a blade 70 as shown in FIG. 3.
Once the fiber preform 80 has been made in this way, injection sectors (not shown in FIG. 3) are put into position around the mold tooling 60 in order to impregnate the preform with a resin that is a precursor of the matrix.
Winding in that way presents drawbacks. Specifically, using intermediate conveyor rollers makes it necessary to provide an extra length of fiber texture, since the fiber texture needs to be held permanently under tension until the end of being wound on the mold tooling. As shown in FIG. 3, at the end of winding an extra length 15 of the fiber texture 10 is present between the support tooling 30 and the mold tooling 60 for the purpose of keeping the fiber texture 10 under tension. The extra length 15 is woven in continuity with the texture 10 that is used for making the preform 80. Since the beginning of weaving the fiber texture 10 corresponds to the end of winding, the extra length 15 is woven at the beginning of the fiber texture 10 and is fastened to the support tooling 30.
An extra length is thus associated with each fiber texture, and it is eliminated when the preform 60 is cut. The extra length 15 is then lost since it cannot be reused. This loss of material increases the cost of fabricating the preform and the cost of the resulting part made of composite material.